Pulmonary atelectasis during paediatric anaesthesia: CT scan evaluation and effect of positive endexpiratory pressure (PEEP).

The case series consisted of ten children, ranged in age from one to three years (median 1.8 yrs), and in body weight from 10.2 to 13.5 kg (median 11.7 kg), in ASA class 1 or 2, all without lung disease. Having undergone general anaesthesia for cranial or abdominal CT scans, the patients were studied for pulmonary morphology. The first pulmonary CT scan was taken five min after induction of general inhalational anaesthesia; preoxygenation was avoided and an intraoperative FiO2</=0.4 was used. Densities in dependent regions of both lungs were observed in all children. After ventilation with PEEP of 5 cmH2O, all the observed densities disappeared without impairment of heart rate, blood pressure, haemoglobin saturation and endtidal CO2 (PECO2). We conclude that the appearance in children of atelectasis cannot be explained by a reabsorption of O2 mechanism and by denitrogenation. However, a PEEP of 5 cmH2O is able both to recruit all the available alveolar units, and to induce the disappearance of atelectasis in dependent lung regions.